Devices for imaging body cavities or passages in vivo are known in the art and include endoscopes and autonomous encapsulated cameras. Endoscopes are flexible or rigid tubes that pass into the body through an orifice or surgical opening, typically into the esophagus via the mouth or into the colon via the rectum. An image is formed at the distal end using a lens and transmitted to the proximal end, outside the body, either by a lens-relay system or by a coherent fiber-optic bundle. A conceptually similar instrument might record an image electronically at the distal end, for example using a CCD or CMOS array, and transfer the image data as an electrical signal to the proximal end through a cable. Endoscopes allow a physician control over the field of view and are well-accepted diagnostic tools. However, they do have a number of limitations, present risks to the patient, and are invasive and uncomfortable for the patient. Their cost restricts their application as routine health-screening tools.
Because of the difficulty traversing a convoluted passage, endoscopes cannot reach the majority of the small intestine. Therefore, special techniques and precautions are required to reach the entirety of the colon, which will add cost. Endoscopic risks include the possible perforation of the bodily organs traversed and complications arising from anesthesia. Moreover, a trade-off must be made among patient pain during the procedure, the health risks and post-procedural down time associated with anesthesia. Endoscopies are necessarily inpatient services that involve a significant amount of time from clinicians and thus are costly.
An alternative in vivo image sensor that addresses many of these problems is capsule endoscope. A camera is housed in a swallowable capsule along with a radio transmitter for transmitting data to a base-station receiver or transceiver. A data recorder outside the body may also be used to receive and record the transmitted data. The data primarily comprises images recorded by the digital camera. The capsule may also include a radio receiver for receiving instructions or other data from a base-station transmitter. Instead of radio-frequency transmission, lower-frequency electromagnetic signals may be used. Power may be supplied inductively from an external inductor to an internal inductor within the capsule or from a battery within the capsule.
An autonomous capsule camera system with on-board data storage was disclosed in the U.S. patent application Ser. No. 11/533,304, entitled “In Vivo Autonomous Camera with On-Board Data Storage or Digital Wireless Transmission in Regulatory Approved Band,” filed on Sep. 19, 2006. This application describes a capsule system using on-board storage such as semiconductor nonvolatile archival memory to store captured images. After the capsule passes from the body, it is retrieved. Capsule housing is opened and the images stored are transferred to a computer workstation for storage and analysis. For capsule images either received through wireless transmission or retrieved from on-board storage, the images will have to be displayed and examined by diagnostician to identify potential anomalies.
Besides the above mentioned forward-looking capsule cameras, there are other types of capsule cameras that provide side view or panoramic view. A side or reverse angle is required in order to view the tissue surface properly. Conventional devices are not able to see such surfaces, since their field of view (FOV) is substantially forward looking. It is important for a physician to see all areas of these organs, as polyps or other irregularities need to be thoroughly observed for an accurate diagnosis. Since conventional capsules are unable to see the hidden areas around the ridges, irregularities may be missed, and critical diagnoses of serious medical conditions may be flawed. A camera configured to capture a panoramic image of an environment surrounding the camera is disclosed in U.S. patent application Ser. No. 11/642,275, entitled “In vivo sensor with panoramic camera” and filed on Dec. 19, 2006. The panoramic camera system is configured with a longitudinal field of view (FOV) defined by a range of view angles relative to a longitudinal axis of the capsule and a latitudinal field of view defined by a panoramic range of azimuth angles about the longitudinal axis such that the camera can capture a panoramic image covering substantially a 360° latitudinal FOV.
Conceptually, multiple individual cameras may be configured to cover completely or substantially a 360° latitudinal FOV. However, such panoramic capsule system may be expensive since multiple image sensors and associated electronics may be required. A cost-effective panoramic capsule system is disclosed in U.S. patent application Ser. No. 11/624,209, entitled “Panoramic Imaging System”, filed on Jan. 17, 2007. The panoramic capsule system uses an optical system configured to combine several fields-of-view to cover a 360° view. Furthermore, the combined fields-of-view is projected onto a single sensor to save cost. Therefore, this single sensor capsule system functions effectively as multiple cameras at a lower cost. The sensor structure and operation to support panoramic view is further described in U.S. patent application Ser. No. 12/323,219 entitled “Camera System with Multiple Pixel Arrays on a Chip”, filed on Nov. 25, 2008 and U.S. patent application Ser. No. 13/626,168, entitled “Camera System with Multiple Pixel Arrays on a Chip”, filed on Sep. 25, 2012.
In an autonomous capsule system, multiple images along with other data are collected during the course when the capsule camera travels through the gastrointestinal (GI) tract. The images and data are usually displayed on a display device for a diagnostician or medical professional to examine. In order to increase the efficiency of examination, the images are displayed continuously as a video with some display control such as display speed, Forward, Reverse, and Stop to allow a user to navigate through the image sequence easily. Presenting the set of collected images as video data can substantially improve the efficiency of examination. However, each image only provides a limited view of a small section of the GI tract. It is desirable to combine the capsule images as a large picture representing a cut-open view of the inner GI tract surface. The large picture can take advantage of the high-resolution large-screen display device to allow a user to visualize more information at the same time. After removing the redundant overlapped areas between images, a larger area of the inner GI tract surface can be viewed at the same time. In addition, the large picture can provide a complete view or a significant portion of the inner GI tract surface. It should be easier and faster for a diagnostician or a medical professional to quickly spot an area of interest, such as a polyp.